Edible collagen sausage casings are made with collagen which is derived from bovine hides or tendons. Such casings are widely used in the manufacture of many different sausage products including dried, smoked sausage. Dried, smoked sausage is widely available in various types such as beef sticks, pepperoni, salami, thuringer and summer sausage. These sausages are usually filled in an edible food casing of animal origin such as collagen. When the sausages are subject to the smoking process, the casing will pick up the color of the smoke. Unfortunately, the smoke will not uniformly color the casing, and therefore, there is a certain amount of nonuniformity of the casing which leads to an asthetically unacceptable product. It is preferred to employ a dyed casing in the manufacture of this type of product. The dye imparts a uniform color to the finished product and also prevents subsequent discoloration in the event of rehydration of the casing which is a common problem with undyed collage casings.
Prior art techniques for dyeing collagen casings have employed edible carriers in order to fix the dyestuff in the casing. For example, the process of U.S. Pat. No. 4,061,786 applies an edible dye to an edible carrier such as cellulose or starch powder, and then incorporates the powder into the extrudable gel and extrudes the resulting admixture to form the dyed casing.
The process U.S. Pat. No. 3,961,085 employs an encapsulating agent to encapsulate the powder of the dyestuff and then introduces the encapsulated dye into the extrusion gel and then extrudes the gel into a casing.
Other methods of incorporating the dye include coating an extruded casing with the dye and fixing the dye on the surface of the casing with heat.
The above-mentioned processes were particularly useful when dyeing the casing a reddish color as there are suitable food-grade red dyes available such as Annato or Bixin.
However, these dyes are not applicable if it is desired to dye the casing a brownish color or a mahogany color. The mahogany color can be characterized as brown with a trace of red. There are very few food-grade brown dyestuffs available which can be used in edible food products.